Greetings, Group.

On a recent trip to London, I happened to be looking out the windows of a
tube train on a deep level track, and noticed a pair of what appeared to be
unshielded, uninsulated copper wires, approximately 8 inches apart from each
other. They were mounted above the usual cables you see inside a tunnel, and
were considerably thinner - just think 30amp cooker cable. (At least, that's
how they looked.)

They'd appear to terminate a few meters before a station. Whereas the larger
cables would appear to either go down below platform level, or behind the
advertising boards, I was unable to see how these terminated - they simply
disappeared.

Can someone cast some light on what these two wires are and do?
Also, purely out of curiosity, what -do- all those thick cables do? I always
assumed tube trains were hooked up to the power and negative tracks.

Thanks in advance,
Dave
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